The present invention relates to an improved knapsack in which the system for securing the strap assembly and/or the belt assembly to the back or frame of the knapsack is fitted with a damper for damping angular pivoting.
A knapsack is constituted by a container or bag, with a strap assembly enabling the knapsack to be secured to the shoulders of the user, and with a belt assembly for securing the knapsack around the waist of the user, said strap and belt assemblies being generally fixed to the back of the bag and optionally to a stiffening frame.
Proposals have already been made in document EP 0 260 959 for a fastening system between the knapsack bag and the strap assembly which allows the strap assembly to pivot angularly relative to the bag. That fastening system comprises a male piece which is secured to the strap assembly and which includes a projecting fixing head, and a female piece secured to the back of the bag, presenting a central recess and means for locking the fixing head once it has penetrated into the central recess. Specifically, the male piece includes a kind of peg made up of a plurality of flexible branches each terminated by a projecting catch, while the female piece has a hole terminated by an annular shoulder. The respective dimensions of the peg and of the hole are such that the peg penetrates into the hole by virtue of its component branches bending, and the two pieces are locked together by the projecting catches extending into the annular shoulder. This allows the male piece to pivot in either direction about the pivot axis, i.e. the axis of the peg, thereby enabling the strap assembly to track movements of the user while traveling.
In a particular embodiment of document EP 0 260 959, provision is made to limit the angular pivoting of the male and female pieces by means of a kind of stud which is provided on the male piece and which penetrates into a groove formed in the female piece. The end uprights of the groove define the maximum angular stroke between the male and female pieces.
Nevertheless, in that document, no attempt is made to damp displacement of the two pieces relative to each other between the two abutments. Thus, depending on the particular movements of the user, jolts can be imparted to the strap assembly whenever the relative angular displacement between the two pieces would otherwise exceed the maximum angular stroke as defined by the abutments.
Document EP 0 628 265 similarly describes a fastening system between the back of a knapsack bag and a belt assembly, which system allows for angular pivoting of the belt assembly relative to the back of the bag by means of a rather complex set of pieces. That document makes provision for a system of abutments that define a maximum angular stroke, and also a set of flexible tongues each having one end fixed securely to a piece forming part of the belt assembly and an opposite end which is free and which penetrates into a respective notch provided in a piece which is secured to the knapsack. During angular pivoting, the tongues are caused to deform, depending on the angular position adopted. Although not explicitly stated in the text of that document, it can be assumed that the tongues do not deform without a certain amount of force being exerted, with said force thus opposing angular pivoting. It should be observed that the presence of the abutments is essential since otherwise the free ends of the flexible tongues could escape from the notches in the event of angular pivoting through too great an amplitude.
The object of the present invention is to provide a knapsack which includes a fastening system allowing angular pivoting between the back of the bag and the strap (and/or belt) assembly but without requiring the presence of abutments for defining the maximum stroke of such pivoting, and which provides progressive damping of the forces involved during such pivoting.
This object is fully achieved by the knapsack of the invention. In conventional manner, the knapsack of the invention comprises a container or bag, a strap assembly for securing the bag to the shoulders of the user, a belt assembly for securing the bag around the waist of the user, and a fastening system for fastening the strap (and/or belt) assembly to the back of the bag, said fastening system comprising a first piece secured to the strap (and/or belt) assembly and a second piece secured to the back of the bag, said pieces co-operating with each other to enable the first and second pieces to be fastened together and to pivot about a pivot axis perpendicular to the back of the bag.
In characteristic manner of the invention, the fastening system comprises:
a) at least one elastomer element secured to one of the two pieces; and
b) engagement means secured to the other piece and engaging the elastomer element at least during pivoting so that during pivoting the engagement means causes the elastomer element to be deformed, thereby opposing said pivoting.
Angular pivoting of the strap (and/or belt) assembly relative to the bag causes the elastomer element to be deformed in its zone adjacent to the means driving it in the pivot direction. Thus, in the fastening system of the invention, there is no abutment defining the maximum angular stroke or pivoting. It is the ability of the elastomer element to deform that absorbs the forces involved during relative movements of the user""s body, and thus of the strap (and/or belt) assembly which tracks such movements. Depending on the relative position and on the structure of the elastomer element and of the first and second pieces, the deformation can be of the compression, traction, twisting, shear, or bending type.
The elastomer used is determined as a function of the volume of the bag and thus of the average weight carried thereby so that the angular pivoting lies in a range of xe2x88x925xc2x0 to +5xc2x0 about a normal position.
The generic term xe2x80x9celastomerxe2x80x9d should naturally be understood to mean not only synthetic elastomers but also rubbers. It is preferable to use a vulcanized elastomer or a thermoplastic elastomer having determined hardness on the Shore A scale.
The engagement means can be of various kinds: it can be constituted by purely mechanical means or by adhesive means. By way of example, when the engagement means are constituted by adhesive means, the two opposite faces of the elastomer element are stuck respectively to the first and second pieces; relative pivoting of the two pieces deforms the element in shear across its thickness. Nevertheless, there is a risk of the elastomer element coming unstuck in use. Mechanical means are therefore preferred.
In a mechanical embodiment, the elastomer element is fixed via two anchor points to the rear face of the first piece and presents at least one hollow zone between the two anchor points; in addition, the front face of the second piece has a projecting stud, said stud penetrating snugly into the hollow zone of the elastomer element when the two pieces are fastened together.
Depending on its direction, angular pivoting of the strap (and/or belt) assembly relative to the back of the bag causes one or other of the two zones of the elastomer element lying between the hollow zone and the two anchor points to be deformed in compression.
The elastomer element preferably includes at least one rib, and the stud is preferably in the form of an elongate shoulder suitable for engaging in the corresponding rib, the ribs and the shoulders extending radially relative to the pivot axis. By means of this particular disposition, the contact area between the elastomer element and the stud is increased thus enabling deformation of the elastomer element to be distributed uniformly during pivoting.
Advantageously, the elastomer element is in the form of an annular or part-annular strip, centered on the pivot axis; in addition the fastening system has two diametrically opposite assemblies each constituted by one or more hollow zones, together with optional radial ribs, and one or more studs, together with optional elongate shoulders.
This particular disposition makes it possible to spread the forces involved during compression of the elastomer strip over both assemblies. The two assemblies in question are preferably disposed symmetrically about the vertical axis (DDxe2x80x2) of the bag so as to obtain a structure that is entirely homogeneous and symmetrical.
The first piece which is secured to the strap (and/or belt) assembly is preferably a male piece having a fixing head which projects from the rear face of said piece, while the second piece which is secured to the back of the bag is a female piece presenting a central recess opening out in its front face, said male and female pieces co-operating with each other to enable the male piece to be fastened to the female piece so as to be capable of pivoting about a pivot axis corresponding to the axis of the fixing head.
The fixing head is preferably mounted to rotate freely relative to the male piece in a housing that opens out into both faces of the male piece; the head is terminated at one end by a handling tab or knob which the user can access via the opening leading into the housing from the front face of the male piece, and at the other end the head is terminated by a T-shaped fastening portion; in addition, the central recess of the female piece carries two lips for retaining the two limbs of the T-shape after the fastening portion of the fixing head has penetrated into the recess and after the handling tab has been turned through a determined angle, preferably of 90xc2x0. This particular disposition enables the male and females pieces to be fastened together without any need to cause said pieces to pivot relative to each other, where such pivoting would be difficult or indeed impossible because of the presence of the studs in the interface between said two pieces. Because it is possible to turn the fixing head in its housing, it suffices to position the two pieces accurately relative to each other, with the studs being received in the hollow zones of the elastomer strip, and with the T-shaped fastening portion of the fixing head penetrating into the recess of the female piece, and then to turn the knob through 90xc2x0 so as to lock the male and female pieces together.
Under such circumstances, it is advantageous for the housing for the fixing head to include an internal abutment and snap-fastening system serving firstly to limit rotation of the knob to a determined angle which is preferably 90xc2x0, and secondly to provide a degree of locking for the fixing head on reaching either of the two positions that are separated by said angle, i.e. a first position in which the front portion of the fixing head is inserted into the recess, and a second position in which it is locked, after being turned.
In order to make it easier to center the male and female pieces, and also in order to distribute the shear forces between said two pieces while the knapsack is being worn, the male and female pieces preferably include two circular portions both centered on the pivot axis, one portion projecting and the other being set back, and said portions being suitable for being received one within the other. The setback circular portion is preferably formed in the female piece, with the projecting circular portion being formed on the male piece.
In a preferred embodiment, the second piece, in particular the female piece, is integrated in the reinforcement for stiffening the knapsack bag; the reinforcement preferably includes a plurality of superposed elements similar to second pieces, in particular female pieces, distributed in its height direction thus enabling the height at which the strap (and/or belt) assembly is positioned relative to the bag to be adjusted.